The present invention relates to a method for reading the addresses on items of mail as claimed in the preamble of claim 1, as well as to a device for carrying out the method as claimed in the preamble of claim 5.
Systems for automatically reading addresses (OCR) are well known in the field of letter processing and are described, for example, in DE 195 31 392 C1. With modern OCR letter sorting systems, processing rates of ten letters per second, i.e. 36,000 letters per hour and more can be achieved. However, the recognition reliability varies greatly depending on the type of lettering and the overall quality of the address information on the surface of the letters. In the case of successful recognition, the respective letter can be provided with a machine-readable barcode. This barcode permits further mechanical processing extending as far as any desired sorting arrangement. In particular, the use of barcodes permits the letters to be sorted extending as far as the sorting level of the postal round during which letters are sorted in accordance with the sequence of their distribution by the postal delivery person.
Since the recognition rates of the automatic reading system vary to a very great extent it is necessary for them to be supported by video coding devices, In this context, the video images of the items of mail which are rejected by the OCR processor are manually coded by video coding personnel at corresponding video coding workstations. In this context, the addresses which are input are converted into a sorting code by means of a directory.
In online video coding systems (OVS) the video image is shown to the operator, while the physical item of mail is held in delaying paths. In these delaying paths, the item of mail is normally kept moving for a time period which is sufficient for the operator to enter the necessary sorting information for the respective image. The customary delaying paths permit a delay between 10 and 30 seconds. The longer the delaying path, the greater the cost and the requirements for maintenance and the physical size of the equipment.
The main problem when using OVS is that the available time is sufficient only to carefully input the zip code (ZIP) or the postcode (PC) unless delaying paths which have an unpractical length are used.
For this reason, special coding methods have been developed for keeping the necessary online delay time as short as possible.
In order to increase the coding productivity and/or to permit all the address elements, i.e. ZIP/PC, road/P.O. Box, addressee/P.O. Box, addressee/company, to be stated, the following essential methods are known:
Preview Coding
In the case of preview coding, the images of two items of mail are represented simultaneously; one above the other. In this context, the lower image is the active one, i.e. its data is coded. After suitable training, it is possible for operators to code the information on the lower image while they are already taking in the address information from the upper image. The upper image then becomes active and the process is continued. With preview coding, it is possible to double operator productivity as a result of a complete overlap of the cognitive and motive functions when coding successive images.
Extraction Coding
Since only the ZIP/PC address elements can be reliably input by the operator given the online delay times which can be achieved in practice, in the case of extraction coding specific key components of parts of the address which relate to the road are input, Extraction coding is usually based on specially developed rules in which a code of a fixed length is used as an access key to an address directory. For example, the Royal Mail uses an extraction formula which is based on the first three and the last two letters In this context, special rules must be committed to memory by the operator in order to avoid excessive address information and to take into account specific differentiating features such as, for example, directions, for example east, west or categories, for example Street, Lane, Road.
Extraction coding has, despite a specific degree of effectiveness, a number of relatively large disadvantages; in particular, complex extraction rules which frequently require the end of a street name to be taken into account, while these components are usually written least clearly. In addition, a significantly high rate of ambiguous extractions take place during which a plurality of entries in one directory correspond to the extraction code so that it is not possible to make an unambiguous sorting decision, Furthermore, it is necessary to take into account the fact that the inputting productivity of the operators is reduced as soon as decisions have to be made by the operator instead of a simple repetitive input on a keyboard.
Offline Coding
Since sufficiently high productivity is not reached in any of the above mentioned coding techniques when pure online coding is used, offline coding systems are also used such as are described in U.S. Pat. No. 4,992,649. In this system, items of mail with addresses which have not been recognized are provided with additional information, a tracking identification (TID). The items of mail which are not recognized are stored externally, while the images of these items of mail are presented to operators for coding, there being no chronological restrictions. The items of mail are then presented to TID reading devices. The TID is logically linked to the input address information. Taking this as a basis, the customary barcode sorting information item can then be applied to the item of mail so that the respective item of mail can be processed as items of mail which have been OCR-read in the customary way. Although the offline video coding method constitutes an effective method of coding all the parts of an address, capacities for the further processing of items of mail which are provided with addresses which are not read, and correspondingly complex logistics, are additionally required.
A sorting system with a plurality of sorters, composed of a sorting section, image recording means and OCR unit, and a plurality of coding stations, has been disclosed in U.S. Pat. No. 4,632,252. The data which has been rejected in the OCR units is assigned to the video coding stations by means of a distributor unit. The data which has been corrected by means of video coding is then sent back via the distributor unit to the sorters from which the rejected data originates.
By including the frequency of the rejected data in each sorter and the performance values features of the video coding stations, the selection of the video coding stations is made in such a way that the throughput rate is as high as possible and the coding stations are utilized to as high a level as possible and as uniformly as possible. By means of this arrangement, in which the individual sorters and the video coding stations are rigidly connected to one another, it is also possible to deal with rejection peaks at a specific sorter.
In order to increase the reading performance it is also known for all the unsuccessfully video coded images, i.e. in which the coding does not correspond to an entry in a corresponding address directory, to be video coded a second time.
This can be carried out by means of the same member of the video coding personnel (said person is given a second chance for correction) or by a different member of the video coding personnel. This image or the reading result is definitively rejected only if this second attempt also fails. A relatively large coding capacity for the second coding process is therefore necessary here, especially since the causes of the failure of correspondence with the entries in the address directories may not only be the coding errors but also errors of the senders or errors in the address directories or address directories which are not up to date.
The statements made with respect to video coding apply of course also to reading devices without an automatic OCR reader.